Roller and image forming apparatus using same

ABSTRACT

Provided is a roller, in particular a conductive roller, capable of suppressing generation of cut debris from a cut surface of an end part of a foam layer in the roller axial direction over a long period of time, and an image forming device using the roller. A roller includes a shaft  1 , a foam layer  2  and at least one film layer  3  sequentially provided on the outer periphery of the shaft. Both end parts in the roller axial direction of the foam layer and the film layer are cut, a filler layer  4  is provided on the cut surface of the cut foam layer and the cut film layer, at least the cut surface of the foam layer is covered with the filler layer, and the filler layer contains a water-based urethane resin.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a National Stage of International Application No.PCT/JP2015/074368 filed Aug. 28, 2015, claiming priority based onJapanese Patent Application No. 2014-179988 filed Sep. 4, 2014, thecontents of all of which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The present invention relates to a roller and an image formation deviceusing the same (hereinafter, also simply referred to as a “device”), andin particular, to a conductive roller used in image formation devicessuch as copying machines, printers and in particular laser beamprinters, and in particular to a roller suitable as a developing rollerand an image formation device using the same.

BACKGROUND ART

In general, in image formation devices using electrophotographicprinting methods such as copying machines, printers, facsimiles, etc.,rollers provided with electrical conductivity are used such as transferrollers, developing rollers, toner supply rollers, electrificationrollers, cleaning rollers, intermediate transfer rollers, belt drivingrollers, etc. in each step of the image formation.

As such a roller member, in order to obtain desired surface roughness,electrical conductivity and hardness etc., conventionally used is onethat are provided with a layer or layers provided on the outer peripheryof a basic structure which is a structure constituted by shaft on whichan elastic layer is formed, the elastic layer being composed of rubber,polymeric elastomer, polymer foam, etc. which was given electricalconductivity by the combination of a conductive agent.

As a technology relating to the improvement of the conductive roller,for example, Patent document 1 describes a conductive roller having acore metal, a substrate provided on the surface thereof and a fillerlayer provided on the cylindrical surface of the substrate which iscomposed of conductive flexible polyurethane foam, wherein a releaseopening for a bubble of conductive flexible polyurethane foam in thecylindrical surface is blocked by the filler layer.

RELATED ART DOCUMENT Patent Document

Patent Document 1: Japanese Unexamined Patent Publication No. H9-262912(Claims etc.)

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, when the elastic layer supported on the outer periphery of theshaft is formed by a foam layer and the end of the shaft is cut in itsaxial direction in order to adjust the roller size and shape, cut wasteis sometimes generated from the end of the foam layer exposed due tocutting. Such cut waste, if transferred to photo sensitizer or paper inan image formation device, is problematic due to the occurrence of animage defect. Although, for dealing with the problem, methods of airspraying and wipe spraying treatment may be used to remove cut debris,they cannot remove it completely.

On the other hand, although it is conceivable to suppress generation ofcut debris by providing a filler layer on a cut surface of a roller endpart subjected to a cut process, since a roller member is driven torotate in an image forming device, it is important to secure durabilityassociated with its use.

Accordingly, an object of the present invention is to provide a roller,in particular a conductive roller, capable of suppressing generation ofcut debris from a cut surface of an end part of a foam layer in theroller axial direction over a long period of time, and an image formingdevice using the roller.

Means for Solving the Problems

The present inventor intensively studied to find that theabove-described problems can be solved by providing a filler layer madeof a specific material on a cut surface of an end part of a rollersubjected to a cut process, thereby completing the present invention.

That is, a roller of the present invention is a roller comprising ashaft, a foam layer and at least one film layer sequentially provided onan outer periphery of the shaft, characterized in that

-   -   both end parts in the roller axial direction of the foam layer        and the film layer are cut, a filler layer is provided on the        cut surface of the cut foam layer and the cut film layer, at        least the cut surface of the foam layer is covered with the        filler layer, and the filler layer contains a water-based        urethane resin.

In the roller of the present invention, preferably, the water-basedurethane resin is ester/ether-based or carbonate-based. In the roller ofthe present invention, preferably, the foam layer is composed of apolyurethane foam having a density of from 0.1 to 0.7 g/cm³. Further, inthe roller of the present invention, preferably, the filler layercontains a silicone-based additive, and suitably, a film thickness ofthe filler layer is from 10 to 100 μm. Still further, the roller of thepresent invention is suitably a conductive roller.

Further, the image forming device of the present invention ischaracterized in that the above-described roller of the presentinvention is mounted thereon.

Effects of the Invention

According to the present invention, by providing a filler layercontaining a water-based urethane resin on cut surfaces of a foam layerand a film layer, it becomes possible to realize a roller capable ofsuppressing generation of cut debris from the cut surface of an end partof the roller axial direction of the foam layer and preventinggeneration of an image failure caused by cut debris over a long periodof time, and an image forming device using the roller.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view illustrating oneconfiguration example of a roller of the present invention.

FIG. 2 is a partial cross-sectional view illustrating one configurationexample of an image forming device of the present invention.

FIG. 3 is a schematic view illustrating a device used for durabilityevaluation in Examples.

MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will now be described withreference to the drawings.

FIG. 1 depicts a longitudinally cross-sectional view of an example of aroller of the present invention. As depicted, the roller 10 of thepresent invention is provided with a shaft 1, a foam layer 2 supportedon the outer periphery of the shaft and at least one film layer coveringthe outer periphery of the foam layer which is a film layer 3 in theillustrated example.

In the roller of the present invention, both ends of the foam layer 2and at least one film layer 3 in the roller axial direction are cut, anda filler layer 4 covering at least a cut surface of the foam layer 2 isprovided on the cut surface of the cut foam layer 2 and at least one cutfilm layer 3. In the present invention, the filler layer 4 ischaracterized by being formed of a material containing a water-basedurethane resin.

In the present invention, by providing a filler layer 4 covering atleast the foam layer 2 on the cut surface to protect the cut surface andeliminate the exposure of the cut surface of the foam layer 2, it becamepossible to effectively suppress generation of cut debris from the cutsurface. On the other hand, when a roller is attached to a cartridge andmounted on a device, the roller contacts and collides with anothermember, so that a filler layer deforms and peels off, which may lose aneffect of suppressing cut debris. However, by using a water-basedurethane resin as the filler layer, it becomes possible to improve thedurability by enhancing the strength and abrasion resistance of thefiller layer and the adhesion to the cut surface. In particular, as willbe described later, when the foam layer 2 is formed of polyurethanefoam, since the foam layer 2 and the filler layer 4 using thewater-based urethane resin have the same functional group, compatibilityis good and adhesiveness is more improved. This makes it possible toprevent an image failure caused by adhesion of cut debris to a photosensitizer or the like in an image forming device over a long period oftime.

The water-based urethane resin used for the filler layer 4 is aself-emulsifying type obtained by emulsifying a urethane resin, and maybe of any type, such as an ether-based, an ester-based, anester/ether-based, and a carbonate-based, and from the viewpoint ofadhesiveness to a cut surface and durability, an ester/ether-based or acarbonate-based is preferably used. The reason why a water-basedurethane resin is used is that in a solvent system, a water-basedurethane resin penetrates into the foam layer 2 and swells the foamlayer 2.

The filler layer 4 preferably contains a silicone-based additive. Byadding a silicone-based additive to a water-based urethane resin, it ispossible to reduce the coefficient of friction of the surface of thefiller layer 4 to be formed, thereby further improving the durability.Specific examples of the silicone-based additive which can be usedinclude acrylic-silicone graft polymer. The addition amount of thesilicone-based additive is preferably from 5 to 30% by mass, and morepreferably from 5 to 10% by mass in the total amount of the water-basedurethane resin and the silicone-based additive in solid content. Inparticular, by containing the silicone-based additive in an amount of 5to 10% by mass, it is possible to provide the filler layer 4 in auniform coating state while sufficiently reducing the frictional force.

The filler layer 4 can be formed by applying a coating liquid preparedby adding a silicone-based additive to a water-based urethane resin, asneeded, to the cut surface using a dispenser, a stamp, a spray, a knifecoater, or the like, then volatilizing, and curing. Specific examples ofthe coating method include a method of scratching and painting the paintsupplied to the cut surface with a dispenser or the like with a doctorknife or the like and a method of spray painting on the cut surface, andas a heating method, a general method may be appropriately used.

Since the filler layer 4 is acceptable so long as it can cover at leastthe cut surface of the foam layer 2, the filler layer 4 may be formedinto the same diameter as that of the roller or a diameter larger thanor equal to the outer diameter of the foam layer 2 and smaller than thatof the roller. The filler layer 4 may be formed specifically, forexample, into an outer diameter of [(outer diameter of the roller)−0μm˜(outer diameter of the roller)−250 μm] although it depends on theroller size.

The thickness of the filler layer 4 may be any thickness as long as itcan completely cover a cut surface of the foam layer 2, and ispreferably from 10 to 100 μm. By setting the film thickness in thisrange, it is possible to accurately attach the roller to a mountingposition when the roller is mounted on a cartridge, while securing thedurability of the filler layer 4.

In the present invention, the only important point is that in a rollerhaving a cut surface of a foam layer at the end of the roller in theaxial direction thereof, at least the cut surface of the foam layer wascovered by a filler layer, and otherwise the constitution may be madeappropriately according to conventional methods and is not particularlylimited.

For example, the shaft 1 is not limited so long as it is wellelectro-conductive, and any shafts can be used, which, for example,include steel metals such as sulfur free cutting steel plated withnickel, zinc or the like, solid core metals made from a metal such asiron, stainless steel, aluminum, etc., metal shafts such as a hollowmetal cylindrical body etc., and shafts made from wellelectro-conductive plastics.

The foam layer 2 is composed of foam, and specifically can be formedfrom elastomer such as polyurethane, silicone rubber,ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber(NBR), natural rubber, styrene-butadiene rubber (SBR), butadiene rubber,isoprene rubber, polynorbornene rubber, butyl rubber, chloroprenerubber, acrylic rubber, epichlorohydrin rubber (ECO), ethylene-vinylacetate copolymer (EVA) and the mixture thereof, and is suitablycomposed of polyurethane foam. According to the present invention,generation of a cut debris can be suppressed, and therefore, a rollerusing polyurethane foam excellent in image characteristics can be usedwithout problems. The foam constituting the foam layer 2 is formed byfoaming chemically the above-described elastomer with a foaming agent orby foaming it mechanically by involving air therein as in the case ofpolyurethane foam.

In addition, since compression permanent deformation performance isimproved when the foam constituting the foam layer 2 is a closed-cellfoam, bubbles in the foam are suitably closed-cell bubbles. In order forbubbles in the foam to be closed-cell, the procedure of foaming theabove-mentioned elastomeric raw material by mechanical stirring of thefoam is suitably adopted.

Raw polyurethane materials for forming the polyurethane foam which aresuitably used for the foam layer 2 are not especially limited so long asthey contain a urethane bond in the resin. As a polyisocyanateconstituting the raw polyurethane material, aromatic isocyanate or thederivative thereof, aliphatic isocyanate or the derivative thereof, andalicyclic isocyanate or the derivative thereof are used. Aromaticisocyanate or the derivative thereof is preferable among them, andtolylenediisocyanate or the derivative thereof, and diphenylmethanediisocyanate or the derivative thereof are particularly suitably used.As tolylenediisocyanate or the derivative thereof, crudetolylenediisocyanate, 2,4-tolylenediisocyanate,2,6-tolylenediisocyanate, the mixture of 2,4-tolylenediisocyanate and2,6-tolylenediisocyanate, the urea modified products thereof, the biuretmodified products thereof, the carbodiimide modified products thereof,and urethane product modified by polyol etc. are used. As diphenylmethane diisocyanate or the derivative thereof, for example,diphenylmethane diisocyanate or the derivative thereof, obtained byphosgenation of diaminodiphenylmethanes or the derivative thereof areused. The derivatives of diaminodiphenylmethane, include polynuclearproducts, and pure diphenylmethane diisocyanate obtained fromdiaminodiphenylmethane, polymeric diphenylmethane diisocyanates obtainedfrom the polynuclear products of diaminodiphenylmethane can be used. Asfor the number of functional groups of polymeric diphenylmethanediisocyanate, a mixture of pure diphenylmethane diisocyanate andpolymeric diphenyl methane diisocyanate having various numbers offunctional groups is usually used, and a mixture having an averagednumber of functional groups preferably from 2.05 to 4.00, morepreferably from 2.50 to 3.50 are used. In addition, derivatives obtainedby the modification of these diphenylmethane diisocyanates orderivatives thereof, for example, such as urethane modification productsmodified by polyol etc., dimers by uretdione formation, isocyanuratemodification products, carbodiimide/uretonimine modification products,allophanate modification products, urea modification products, biuretmodification products can be also used. Further, a blend of severalkinds of diphenylmethane diisocyanates and the derivatives thereof canbe also used.

Polyol components constituting raw polyurethane materials can be usedwhich include polyether polyol from the addition polymerization ofethylene oxide with propylene oxide, polytetramethylene ether glycol,polyester polyol from the condensation of the acid component and theglycol component, polyester polyol from the ring-opening polymerizationof caprolactone, and polycarbonate diol. Polyether polyol from theaddition polymerization of ethylene oxide with propylene oxide includeproducts from the addition polymerization of ethylene oxide withpropylene oxide, for example, by using, as a starting material, water,propylene glycol, ethylene glycol, glycerin, trimethylolpropane, hexanetriol, triethanolamine, diglycerine, pentaerythritol, ethylenediamine,methyl glucoside, aromatic diamine, sorbitol, sucrose, phosphoric acid,etc., and particularly suitable is a product from water, propyleneglycol, ethylene glycol, glycerin, trimethylolpropane, hexane triol usedas a starting material.

As for the ratio and microstructure of added ethylene oxide andpropylene oxide, the ratio of ethylene oxide is preferably from 2 to 95%by mass, more preferably from 5 to 90% by mass. In particular, thepolyether polyol having ethylene oxide added on the terminal thereof ispreferably used. The arrangement of ethylene oxide and propylene oxidein the molecular chain is preferably random. The molecular weight ofthis polyether polyol, bifunctional when obtained from water, propyleneglycol and ethylene glycol as starting materials, is preferably in therange from 300 to 6000 by weight-average molecular weight, particularlypreferably from 400 to 3000. The molecular weight of the polyetherpolyol, trifunctional when obtained from glycerin, trimethylolpropaneand hexane triol as starting materials, is preferably in the range from900 to 9000 by weight-average molecular weight, and particularlypreferably from 1500 to 6000. A blend of the bifunctional polyol and thetrifunctional polyol can be appropriately used.

Polytetramethylene ether glycol is obtained, for example, from cationicpolymerization of tetrahydrofuran, and the product having weight-averagemolecular weight in the range from 400 to 4000, particularly from 650 to3000 is preferably used. It is also preferable to blendpolytetramethylene ether glycols with different molecular weights. Inaddition, polytetramethylene ether glycols obtained fromcopolymerization of alkylene oxides such as ethylene oxide and propyleneoxide can be also used. It is also preferable to use a blend ofpolytetramethylene ether glycol and polyether polyol from additionpolymerization of ethylene oxide with propylene oxide, and in this case,it is preferably used so that the ratio of polytetramethylene etherglycol to polyether polyol from addition polymerization of ethyleneoxide with propylene oxide is within the range from 95:5 to 20:80 bymass, and particularly from 90:10 to 50:50. Polymer polyol ofacrylonitrile-modified polyol, polyol of melamine added to polyol, diolssuch as butane diol, polyols such as trimethylolpropane and thederivatives thereof can be used in combination with the above-mentionedpolyol components.

Polyol may be prepolymerized by polyisocyanate in advance, and themethods include a method in which polyol and polyisocyanate are put intoa suitable vessel, sufficiently stirred and kept at 30 to 90° C., morepreferably 40 to 70° C., for 6 to 240 hours, more preferably for 24 to72 hours. In this case, the ratio of the quantities of polyol andpolyisocyanate are preferably adjusted so that the isocyanate contentratio of the prepolymer to be obtained is from 4 to 30% by mass, morepreferably from 6 to 15% by mass. If the isocyanate content ratio isless than 4% by mass, the stability of the prepolymer is damaged, andthe prepolymer may be hardened during storage and not be able to beprovided for use. When the isocyanate content ratio exceeds 30% by mass,polyisocyanate content that has not been prepolymerized increases, andsince this polyisocyanate is hardened with polyol component to be usedin a later polyurethane hardening reaction, via a reaction mechanismsimilar to a one-shot process that does not undergo prepolymerizationreaction, the advantage of the prepolymer method is diminished. Aspolyol components, when isocyanate component is used which is inprepolymer of polyol prepolymerized in advance by polyisocyanate, diolssuch as ethylene glycol and butane diol, polyols such astrimethylolpropane and sorbitol, and the derivatives thereof can be usedin addition to the above-mentioned polyol components.

To the raw polyurethane material can be added a conductive agent such asan ionic conducting agent and an electro-conductive agent, a fillermaterial such as carbon black and inorganic carbonate, an antioxidantsuch as phenol and phenylamine, a friction-reducing agent, and a chargeadjustment agent, etc. Examples of the ionic conducting agent includeammonium salts such as perchlorate, chlorate, hydrochloride, bromate,iodate, fluoroborate, sulfate, ethylsulfonate, carboxylate, sulfonate oftetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (forexample, lauryl trimethyl ammonium), hexadecyl trimethyl ammonium,octadecyl trimethyl ammonium (for example, stearyl trimethyl ammonium),benzyl trimethyl ammonium, modified fat dimethylethyl ammonium, etc.,and perchlorate, chlorate, hydrochloride, bromate, iodate, fluoroborate,trifluoromethylsulfonate, sulfonate of alkali and alkaline earth metalssuch as lithium, sodium, potassium, calcium, magnesium. Examples of theelectro-conductive agent include conductive carbons such as Ketjenblack, acetylene black; carbons for rubber such as SAF, ISAF, HAF, FEF,GPF, SRF, FT, MT; oxidation-treated carbon for ink, thermaldecomposition carbon, natural graphite, artificial graphite;electro-conductive metal oxides such as tin oxide, titanium oxide, zincoxide; metals such as nickel, copper, silver, germanium. Theseconductive agents may be used alone or in a mixture of more than orequal to two of them. The blending amount thereof is not particularlylimited and can be appropriately selected as desired, and the ratio isusually from 0.1 to 40 parts by mass, preferably from 0.3 to 20 parts bymass with respect to 100 parts by mass of the raw polyurethane material.

Catalysts used in the hardening reaction of the raw polyurethanematerials include monoamines such as triethylamine and dimethylcyclohexylamine, diamines such as tetramethylethylene diamine,tetramethyl propane diamine and tetramethyl hexane diamine, triaminessuch as pentamethyldiethylene triamine, pentamethyldipropylene triamine,tetra-methylguanidine, cyclic amines such as triethylenediamine,dimethyl piperazine, methylethyl piperazine, methyl morpholine,dimethylaminoethyl morpholine, dimethyl imidazole, alcoholic amines suchas dimethylamino ethanol, dimethylaminoethoxy ethanol,trimethylaminoethylethanol amine, methylhydroxyethyl piperazine,hydroxyethyl morpholine, ether amines such asbis(dimethylaminoethyl)ether, ethylene glycol bis(dimethyl)amino propylether, and organometallic compounds such as stannous octoate, dibutyltin diacetate, dibutyl tin dilaurate, dibutyl tin mercaptide, dibutyltin thiocarboxylate, dibutyl tin dimaleate, dioctyl tin mercaptide,dioctyl tin thiocarboxylate, phenyl mercury propionate, lead octenoate.These catalysts can be used alone or in combination of two or more ofthem.

In the present invention, it is preferable that a silicone foamstabilizer and various surfactants are combined into the rawpolyurethane materials for stabilizing the cells in the foam material.As the silicone foam stabilizer, dimethylpolysiloxane-polyoxyalkylenecopolymer, or the like is suitably used, and particularly preferable isthe copolymer having the dimethylpolysiloxane moiety of molecular weightfrom 350 to 15000 and the polyoxyalkylene moiety of molecular weightfrom 200 to 4000. As for the molecular structure of the polyoxyalkylenemoiety, the addition polymer of ethylene oxide and the co-additionpolymer of ethylene oxide and propylene oxide are preferable, and themolecular terminals of the polymers are also preferably ethylene oxide.The surfactants include ionic surfactants such as cationic surfactants,anionic surfactants and amphoteric surfactants, and non-ionicsurfactants such as various polyethers and various polyesters. Theblending amount of the silicone foam stabilizer and the varioussurfactants are preferably from 0.1 to 10 parts by mass, more preferablyfrom 0.5 to 5 parts by mass to 100 parts by mass of the raw polyurethanematerial.

The polyurethane foam used in the present invention preferably has adensity within the range from 0.1 to 0.7 g/cm³, more preferably from0.50 to 0.65 g/cm³. In particular, when polyurethane foam is used whichhas a low density roughly within these ranges, cut waste is likely tooccur, and the application of the present invention is effective. Toolow and too high densities are both undesirable because the too lowdensity leads to the coarsening of the bubble, and the too high densityleads to the worsening of roller performance.

The ASKER C hardness of the polyurethane foam is preferably from 15 to70°, more preferably from 15 to 45°. In the present invention, themechanical floss method, the water foaming method, the foaming agentfloss method, etc., which are conventionally used, can be used as amethod of foaming in advance the raw polyurethane material, and themechanical floss method, which performs foaming by mechanical stirringwhile mixing inactive gas, is preferably used regarding obtainingpolyurethane foam of the closed-cell foam structure having a suitabledensity and hardness. Any inactive gasses used in the mechanical flossmethod are acceptable so long as they are inactive gas in polyurethanereaction, and include gasses non-reactive to the raw polyurethanematerials such as nitrogen, carbon dioxide and dry air as well asinactive gasses in a narrow sense such as helium, argon, xenon, radonand krypton. By injecting the foamed raw polyurethane material into ametal mold, followed by the hardening thereof, polyurethane foam can beobtained which has self-skin layer (thin stratified film) formed on thepart of the foam in contact to the metal mold. At that time, a method ofcoating with fluoro-resin etc. the inner surface of the metal mold cangive mold-releasing property to the metal mold.

The molding conditions of the foam layer 2 is not particularly limitedand can be obey usually conditions, and for example, the foam layer 2can be obtained by starting the foaming of the raw polyurethane materialat a temperature within the range from 15 to 80° C., preferably from 20to 65° C., and completing injection into the metal mold in which shaft 1is placed, and then performing cure at a temperature from about 70 to120° C., followed by removal of the product from the mold.

In the present invention, at least one film layer is formed on the outerperiphery of the foam layer 2. Although in an example depicted in FIG. 1one film layer 3 as a surface layer forming a roller surface is providedon the outer periphery of the foam layer 2, two film layers of anintermediate layer and a surface layer can be also provided withoutlimitation, and moreover, other functional layers may be added.

For example, the surface layer can be formed by solvent-based paintssuch as urethane-based, acrylic-based, acrylic urethane-based andfluorine-based ones, and the surface roughness of the layer can beadjusted by containing spherical microparticles made of urethane, acryl,silica, etc. The surface roughness of such a surface layer is usuallyless than or equal to 2 μm, particularly preferably within the rangefrom 0.5 to 1.5 μm based on the JIS arithmetic average roughness Ra.Desired electrical conductivity can be given by appropriately containingthe above-mentioned ionic conductive agent and the electron conductiveagent as a conductive agent. Although the thickness of the surface layeris not particularly limited, it may be usually from 1 to 50 μm,particularly from about 1 to about 40 μm.

The intermediate layer may be a water-based paint containing aconductive agent, and any one or at least two types selected from thegroup consisting of rubber-based, urethane-based and acrylic-basedpaints can be suitably used as the water-based paint. Latex such asnatural rubber (NR), chloroprene rubber (CR), nitrile rubber (NBR) andstyrene-butadiene rubber (SBR) can be appropriately used as therubber-based paint, ether-based, ester-based emulsions and dispersionsas the urethane-based paint, and acryl, acrylic styrene emulsions etc.as the acrylic-based paint. The same conductive agents as thosementioned above with respect to the foam layer 2 can be used asconductive agents contained in the paints without particular limitation.In addition, vulcanizers, vulcanization enhancers, rubber antioxidants,and the like can be appropriately added to the intermediate layer asdesired.

The thickness of the intermediate layer is usually within the range from10 to 100 μm, particularly from 30 to 80 μm. When the thickness is lessthan 10 μm, the solvent shielding effect for the foam layer and thefiller effect for preventing oozing of contaminant from the lower layerside become insufficient, resulting in solvent erosion that makesimpossible to provide a desired surface roughness. On the other hand,when the thickness exceeds 100 μm, the intermediate layer cannot followthe softness of the foam layer 2, causing a crack and a peeling, thehardening of the roller itself, which could lead to a defect relating tothe roller performance such as toner damage.

The intermediate layer can be formed into one or at least two layers byapplying the above-mentioned water-based paint onto foam layer 2.Well-known procedures can be used as methods of coating the intermediatelayer, which include, but are not limited to, dip coating, spray coatingand roll-coater coating, and dip coating is suitably used. The microhardness of the intermediate layer is suitably within the range from 10to 45° for the film thickness of 500 μm, and the hardness roughly withinthis range can realize desired roller hardness for the finally obtainedroller surface. The micro hardness can be measured, for example, byMicro Durometer Model MD-1.

The roller of the present invention is suitable as a conductive rollerused in electrophotographic image forming devices etc. and can besuitably used specifically, for example, as various roller members suchas developing rollers, electrification rollers, transfer rollers, tonersupply rollers and cleaning rollers, and is particularly useful as adeveloping roller.

The roller of the present invention can be manufactured as follows: Atfirst, a foam layer is formed on the outer periphery of a shaft bymolding; Then, at least one film layer, specifically for example, theabove-mentioned surface layer is directly formed, or an intermediatelayer and the surface layer are sequentially formed by coating on theformed foam layer; Then, the formed foam layer and the film layer arecut at the both ends of the roller in the axial direction thereof,wherein cases of cutting the foam layer and the film layer at the bothends of the roller in the axial direction thereof include a case ofcutting the end parts of the roller expanded by molding and a case ofadjusting the size of the roller from the view point of the appearanceof the roller; Then, by the above-mentioned techniques, the filler layerin a size enough to cover at least the foam layer is provided on the cutsurfaces of the cut foam and film layers, and thus the roller of thepresent invention can be obtained.

Further, the image forming device of the present invention ischaracterized in that the roller of the above present invention,especially the conductive roller, the developing roller among others ismounted thereon, thereby enabling to solve the problem of the occurrenceof an image defect due to the attachment of cut waste onto photosensitizer etc. FIG. 2 depicts a partial cross-sectional view of anexample of the image forming device of the present invention. In theillustrated image forming device of the present invention, there areprovided an image forming body 21, such as photo sensitizer, retainingan electrostatic latent image, a developing roller 10, in contact to theimage forming body 21, for visualizing the electrostatic latent image bythe adhesion of toner 20 supported on the surface of the roller thereto,and a toner supply roller 22 for supplying the toner 20 to thedeveloping roller 10, and image formation is performed by a series ofprocesses which convey the toner 20 from a toner container 23 via thetoner supply roller 22 and the developing roller 10 to the image formingbody 21.

In the illustrated image forming device, the image forming body 21 iselectrified to a constant potential by an electrification roller 25, andthen, an electrostatic latent image is formed on the image forming body21 by an exposure device (not illustrated). Then, by the rotation of thetoner supply roller 22, the developing roller 10 and the image formingbody 21 in the direction of the arrow in the figure, the toner 20 ontoner supply roller 22 is sent via the developing roller 10 to the imageforming body 21. The toner 20 on the developing roller 10 is shaped intoa uniform thin layer by a layering blade 24, and by the rotation of thedeveloping roller 10 and the image forming body 21 in contact with eachother, the toner 20 from developing roller 10 adheres to theelectrostatic latent image in the image forming body 21, resulting inthe visualization of the latent image. The toner 20 adhering to thelatent image is transferred by the transfer roller 26 to recordingmedium such as paper, and the toner 20 remaining on the image formingbody 21 after the transfer is removed by a cleaning blade 28 in acleaning part 27. The image formation device of the present inventionmay be further provided with well-known compartments (not illustrated)used in conventional image forming devices.

EXAMPLES

The present invention will now be described in detail by using Examples.First of all, polyurethane foam was supported on the outer periphery ofa shaft (ø6 mm, 260 mm in length, material type: sulfur free cuttingsteel) by the mechanical floss method. The density of this polyurethanefoam was 0.60 g/cm³. In particular, a raw polyurethane material composedof an isocyanate component (prepolymerized isocyanate TDI+polyetherpolyol) of 100 parts by mass and a polyol component (polyether polyol)of 20 parts by mass, carbon-black (acetylene black) of 2 parts by mass,an ionic conducting agent (sodium perchlorate) of 0.2 parts by mass wasprepared, and this raw polyurethane material was mechanically stirred,mixed with dry air by mixier, and foamed. The polyurethane-foam materialwas injected into a metal cylindrical split mold which was provided witha hole provided at the end thereof for penetrating the shaft and a metalcap placed for supporting the shaft. Inside the mold, the shaft wasplaced, with adhesive applied onto the outer periphery thereof. Then,the mold with polyurethane-foam material injected therein was left in ahot wind oven adjusted to be at 110° C. for one hour to allow thepolyurethane-foam material to harden. The hardened polyurethane foam wasreleased from the mold and dip-coated with CR rubber latex paintcombined with carbon black (Ketjen black) to form an intermediate layerof a film thickness of 60 μm on the outer periphery of the foam layer.Then, the foam was dip-coated with polyurethane solvent-based paintcombined with spherical polyurethane particles of D⁵⁰=10 μm and carbonblack (acetylene black) to form a surface layer of a film thickness of15 μm.

The roller body of the roller obtained above was cut at both ends of theroller in the axial direction thereof so that the size of the rollerbody was ø11.5 mm and 240 mm in length. Then, on the cut surface of theroller body, each of the filler layers described in the following Tablewas formed to obtain the sample rollers of Examples. In the case of aliquid adhesive, the filler layers were formed within the cut surface ofø11.5 mm by a seal coating (a transfer method by a seal-shaped jig)followed by heating. In the case of a hot melt adhesive, a sheet-shapedone was cut into a ring shape having an outer diameter of 11.5 mm, andwas attached and welded by a hot pressing method. Further, in the caseof washers, those made of stainless steel and polypropylene having anouter diameter of 11.5 mm were mounted by pushing them into a cutsurface of the roller body.

<Evaluation Method>

Each of the obtained sample rollers was incorporated in a commerciallyavailable laser beam printer (LBP 7200C, manufactured by Canon Inc.),and 100 sheets of printing durability test was carried out. The resultswere evaluated by visual observation of the printed images, and thepresence or absence (∘ when no failure was generated, x when a failurewas generated) of an image failure due to cut debris generated from acut surface, and the presence or absence of a failure such as peeling ofan adhesive in a filler layer after a printing test was evaluated.

Using the device illustrated in FIG. 3, the durability of cases in whicha filler layer of each sample roller contacted and collided with anothermember in the device was evaluated. Specifically, with respect to an endpart 30E of the roller body where a filler layer of each sample roller30 was formed, a ring-shaped member 31 (inner diameter: 6 mm, outerdiameter: 11.5 mm) made of polyacetal (POM) resin commonly used as acommercially available printer material was pressed with a load F of 1.5N, and each sample roller 30 was rotated at 200 rpm to measure the timeuntil scraping, peeling, and deformation of the filler layer occurred.Reference numeral 32 in the drawing indicates a motor. Evaluationcriteria are as follows.

⊚: No scraping or the like occurred in 3 min.

∘: Scraping or the like occurred in 3 min.

Δ: Scraping or the like occurred in 2 min.

x: Scraping or the like occurred in 1 min.

The results are listed on the following table.

TABLE 1 Comparative Comparative Comparative Comparative Example 1Example 2 Example 3 Example 1 Example 2 Example 3 Example 4 Filler TypeLiquid Liquid Liquid Liquid Liquid Liquid Liquid layer adhesive adhesiveadhesive adhesive adhesive adhesive adhesive Structure Water-basedWater-based Water-based Synthetic Acryl *⁵ Vinyl Epoxy *⁷ urethaneurethane urethane rubber *⁴ acetate *⁶ resin *¹ resin *² resin *³ Filmthickness 50 50 50 50 50 50 50 (μm) Presence or ◯ ◯ ◯ ◯ ◯ ◯ ◯ absence ofcut debris Presence of None None None None None None None absence ofpeeling of adhesive Durability ◯ ⊚ ⊚ Δ Δ Δ Δ *¹) UM700, manufactured byCEMEDINE Co., Ltd. *²) Ester/ether-based urethane, SUPERFLEX 150 (solidcontent 30% by mass), manufactured by DKS Co. Ltd. *³) Carbonate-basedurethane (solid content 30% by mass, the breaking stress 48N/mm²,breaking strain 340%, and tensile stress at 100% elongation 9.8N/mm² ofa material of each filler layer, measured in accordance with a tensiletest of JIS K 7127) *⁴) 575, manufactured by CEMEDINE Co., Ltd. *⁵)Y610, manufactured by CEMEDINE Co., Ltd. *⁶) CH38, manufactured byKonishi Co. Ltd. *⁷) EP007, manufactured by CEMEDINE Co., Ltd.

TABLE 2 Comparative Comparative Comparative Comparative ComparativeComparative Comparative Example 5 Example 6 Example 7 Example 8 Example9 Example 10 Example 11 Filler Type Liquid Hot melt Hot melt Hot meltHot melt Washer Washer layer adhesive adhesive adhesive adhesiveadhesive Structure Silicone *⁸ Urethane- Vinyl Polyolefin- SyntheticStainless Polypropylene based *⁹ acetate- based *¹¹ rubber *¹² based *¹⁰Film thickness 50 50 50 50 50 1000 200 (μm) Presence or ○ ○ ○ ○ ○ ○ ○absence of cut debris Presence of None None None None None None Noneabsence of peeling of adhesive Durability Δ x x x x Δ Δ *⁸) SILMATE82,manufactured by Toshiba Corporation *⁹) ECELLENT, manufactured bySheedom Co. Ltd. *¹⁰) HM224, manufactured by CEMEDINE Co., Ltd. *¹¹)HM712, manufactured by CEMEDINE Co., Ltd. *¹²) HHM650-2, manufactured byCEMEDINE Co., Ltd.

As listed on the above table, in any of the filler materials, it ispossible to prevent occurrence of cut debris, there was no peeling ofthe filler layer after the printing test. From the viewpoint ofdurability, in each of the Examples in which a filler layer was formedusing a liquid adhesive containing a water-based resin, there was nooccurrence of scraping or the like in 2 min. In the Comparative Exampleusing another type of liquid adhesive, scraping or the like occurred in2 minutes. In the Comparative Example using a hot melt adhesive,scraping or the like occurred in 1 minute. In the Comparative Exampleusing a washer, the washer got out around an axis in 2 minutes.

Next, using a water-based urethane resin (ester/ether urethane,SUPERFLEX 150, manufactured by DKS Co., Ltd.) and silicone-basedadditive (US450, manufactured by Toagosei Co., Ltd.) in a blendingamount (based on solid content) listed on the following table, a fillerlayer was formed with a film thickness of 50 μm in the same manner as inthe case of the above-described liquid adhesive to prepare a sampleroller of each Example.

With respect to each of the obtained sample rollers, the coating stateof the filler layer was visually observed, and the static frictioncoefficient of the surface of the filler layer was measured three times,and the average value thereof was determined.

Using the apparatus illustrated in FIG. 3, the durability in cases inwhich the filler layer of each sample roller contacted and collided withanother member in a device was evaluated in the same manner as describedabove. Evaluation criteria are as follows. The results are listed incombination on the table below.

⊚⊚: No scraping or the like occurred in 4 min.

⊚: No scraping or the like occurred in 3 min. Scraping or the likeoccurred in 4 min.

TABLE 3 Static % by % by Coating coefficient Material mass Material massstate of friction Durability Example Water-based 100 — 0 Good 0.53 ⊚ 2urethane resin *² Example Water-based 95 Silicone-based 5 Good 0.31 ⊚ 4urethane additive *¹³ resin *² Example Water-based 90 Silicone-based 10Good 0.15 ⊚⊚ 5 urethane additive *¹³ resin *² Example Water-based 80Silicone-based 20 Sea-island 0.15 ⊚⊚ 6 urethane additive *¹³ shape resin*² Example Water-based 70 Silicone-based 30 Sea-island 0.15 ⊚⊚ 7urethane additive *¹³ shape resin *² *¹³) Acryl-silicone graft polymer,US450 (solid content 30% by mass), manufactured by Toagosei Co., Ltd.

As listed on the above table, it was confirmed that when asilicone-based additive was added to the water-based urethane resin inthe filler layer, the friction coefficient was reduced, and thedurability was improved accordingly. On the other hand, it was foundthat a urethane component and a silicone component were separated whenthe amount of the silicone-based additive was increased, and the coatingstate deteriorated.

Next, with the use of a water-based urethane resin (ester/ether-basedurethane, SUPERFLEX 150, manufactured by DKS Co., Ltd.), the thicknesswas changed as listed on the Table below to form a filler layer in thesame manner as in the case of the liquid adhesive, and a sample rollerof each Example was manufactured.

Using the device illustrated in FIG. 3, the durability in cases in whichthe filler layer of each sample roller contacted and collided withanother member in the device was evaluated in the same manner asdescribed above. Evaluation criteria are as follows. The results arelisted in combination on the table below.

⊚: No scraping or the like occurred in 3 min.

◯: Scraping or the like occurred in 3 min.

TABLE 4 Film thickness (μm) Coating state Durability Example 8 10 Good ◯Example 9 25 Good ⊚ Example 2 50 Good ⊚ Example 10 75 Good ⊚ Example 11100 Good ◯

As listed on the above table, it was confirmed that a sufficientdurability can be obtained while securing a favorable coating state evenwhen the film thickness of the filler layer using the water basedurethane resin was changed.

DESCRIPTION OF SYMBOLS

1 shaft

2 foam layer

3 film layer

4 filler layer

10 roller (developing roller)

20 toner

21 image forming body

22 toner supply roller

23 toner container

24 layering blade

25 electrification roller

26 transfer roller

27 cleaning part

28 cleaning blade

30 sample roller

30E end part of roller body

31 ring-shaped member

32 motor

The invention claimed is:
 1. A roller comprising a shaft, a foam layerand at least one film layer sequentially provided on an outer peripheryof the shaft, characterized in that both end parts in the roller axialdirection of the foam layer and the film layer are cut, a filler layeris provided on the cut surface of the cut foam layer and the cut filmlayer, at least the cut surface of the foam layer is covered with thefiller layer, and the filler layer contains a water-based urethaneresin, wherein the filler layer contains acrylic-silicone graft polymer.2. The roller according to claim 1, wherein the water-based urethaneresin is ester/ether-based or carbonate-based.
 3. The roller accordingto claim 1, wherein the foam layer is composed of a polyurethane foamhaving a density of from 0.1 to 0.7 g/cm³.
 4. The roller according toclaim 1, wherein a film thickness of the filler layer is from 10 to 100μm.
 5. The roller according to claim 1 which is a conductive roller. 6.An image forming device is characterized in that the roller according toclaim 1 is mounted thereon.